让包含EditText控件的容器获得焦点
android:focusableInTouchMode="true"
<requestFocus/>
例如
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_login"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:focusableInTouchMode="true"
tools:context=".LoginActivity">
<requestFocus/>
